datetime to Unix timestamp with millisecond precision

Question

I'm trying to do something really simple, convert a datetime object three days into the future into a Unix UTC timestamp:

import datetime, time then = datetime.datetime.now() + datetime.timedelta(days=3) # Method 1 print then.strftime("%s") # Method 2 print time.mktime(then.timetuple()) # Method 3  print time.mktime(then.timetuple()) * 1000 

Method 1 and 2 give me Unix time in seconds, not milliseconds, and method 3 gives me milliseconds with no actual millisecond precision.

When I simply print then, I get datetime.datetime(2011, 11, 19, 15, 16, 8, 278271), so I know that the precision is available for milliseconds. How can I get a Unix timestamp with actual millisecond precision? If it's returned as a float and I have to flatten it to an an int, that's fine. Is there a solution I'm looking for that does this?

Answer 1

Datetime objects have a field named microsecond. So one way to achieve what you need is:

time.mktime(then.timetuple())*1e3 + then.microsecond/1e3 

This returns milliseconds since UNIX epoch with the required precision.

Answer 2

In Python 3.3 and above, which support the datetime.timestamp() method, you can do this:

from datetime import datetime, timezone, timedelta  (datetime.now(timezone.utc) + timedelta(days=3)).timestamp() * 1e3